“He’s an historian, but that doesn’t give him the right to rewrite history,” Mr. Romney said. Mr. Gingrich has tried to deflect criticism about the House ethics investigation into his use of a tax-exempt organization; in 1997 the House reprimanded Mr. Gingrich, then the House speaker, and fined him $300,000. He was later cleared by the IRS.

“He may be a great guy with a lot of great ideas, but he is not the leader we need at a critical time,” Mr. Romney added in a speech at a shipbuilding company.

Mr. Romney exuded confidence about his chances in Florida’s Tuesday primary as public opinion surveys have begun to turn in his favor. “I just feel like things are going in our direction, I am hoping for a big turn out, and I think we are going to win here, I sure hope so.”

Mr. Gingrich for his part is pitching that he’s more electable because he is a solid conservative. At a campaign event in Port St. Lucie, he painted Mr. Romney as a moderate, and said a moderate will never beat President Barack Obama in November.

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